Cold drawing cylinder is made of hot-rolled tube drawing, hot-rolled tube material, specification, quality selection of appropriate or not directly affects the drawing and the finished product quality. When select material should be paid attention to the following:

(1) in general in strength guarantee when select material, selection of low hardness and plastic materials;

(2) steel pipe specifications should be selected side impact beams according to the specifications of the finished product, guarantee its extension rate from twenty percent to forty percent; Elongation is too small, intensity on the surface of the finished product can't guarantee anything, too, make the drawing to;

(3) the material surface can't have a pit, ****, ****, serious defects such as folding, scarring, elliptic;

(4) the best selection of steel tube placement after hot rolling 0.5 ~ 2 a, time is too short, steel pipe surface rust shallow, time is too long, steel pipe surface rust too deep, these can lead to inadequate steel tube surface pretreatment, thus affecting the surface quality of the product.

Before processing

Without the pretreatment of steel tube, cold drawn with the steel pipe surface and excessive coefficient of friction between mold and make the drawing cannot be; Only after pretreatment process, the steel pipe to rust removing, and through the phosphating, saponification, such as processing, make the inside and outside surface to form a
Kind of dense metal soap film, to reduce the steel tube and the friction between mold, so as to ensure the smooth progress of drawing. At the same time, through pretreatment can reduce side impact door beams the attrition rate mould, improve the yield and efficiency, and make the processed products light
Uniform sliding, antirust effect is good.

Steel pipe pretreatment should be paid attention to the following:

(1) the pickling thoroughly, once found not free of rust, needs to pickling.

(2) production, often should test the phosphating liquid and saponification liquid composition concentration, to ensure that the phosphating liquid and saponification liquid production index, found short of indicators, shall be prepared in the timely.

(3) we will strictly control the temperature of the treatment fluid and operation time.

The design of the mould
Cold drawn pipe is under the action of force, through a certain shape, size of mould drawing, and mold size precision, surface quality directly affect the dimensional precision and quality of the finished product.

Mold design should pay attention to the following aspects:

(1) determine the size of internal and external aluminium coated steel tube mold diameter of the finished product should consider cold drawn the springback amount, generally low hardness, small deformation of material, the springback amount is small, high hardness, large deformation of material, the springback amount;

(2) the surface of the mold to have lower roughness requirements, general value lower than the finished one to two level;

(3) the mold material USES high strength wear resistant materials.